Project Summary Age-related kidney diseases, including chronic kidney disease (CKD) and acute kidney injury (AKI) are major health problems and an economic burden worldwide. In the U.S. alone 30 million people are affected by CKD disease, although the vast majority of these individuals are unaware of their condition. A coexisting disease, a new medication, or a surgical procedure can overstress the already compromised kidney resilience and result in AKI, with risk for end stage renal disease and death. Age affects the regenerative capacity of the kidney and is a major risk factor for developing renal disease. However, the degree of kidney resilience in the aged population varies significantly among individuals. Therefore, a diagnostic test that screens for reduced kidney resilience, specifically in older patients, could aid the physician in selecting therapies that are not only efficacious but tolerable by the patient?s kidneys. Currently, such a test does not exist. The proposed project aims to develop a test for assessing the resilience status of a patient?s kidneys. The test involves collecting living urine-derived renal progenitor cells (UPCs) from a patient?s urine sample, growing them into functional kidney tubules in a microfluidic chip, and subjecting the tubules to conditions that challenge kidney resilience. The response of the tubules grown from the patient?s own UPCs provide information about that patient?s kidney resilience and can be used by the physician to optimize treatment choices. Assay readout will include biomarkers of mitochondrial health, reactive oxygen species, lysosomal activity, as well as cell survival, proliferation, and polarity. UPCs are the cell source of choice for building a renal resilience in-vitro model because these cells reflect the degree of kidney resilience/dysfunction of the donor?even when cultured in vitro. The aging signature of UPCs in cell culture, as in vivo, correlates with a loss of stem-cell specific markers and reduced proliferation potential. UPCs from older individuals have been shown to proliferate less than those from younger individuals. Aim 1 of the project is to establish that in-vitro kidney tubules generated from UPCs replicate kidney proximal tubule biomarkers both in young and aged individuals (Milestone 1) and to measure and compare biomarkers for mitochondrial health, reactive oxygen species, lysosomal activity, cell survival, cell proliferation, and cell polarity in chips derived from young and aged individuals (Milestone 2). Aim 2 is to then use these biomarkers for establishing the range of cellular resiliency in kidney chips from young and aged individuals in response to stress conditions, such as transient hypoxia (Milestone 3) and exposure to nephrotoxic compound cisplatin (Milestone 4). The purpose of Aim 2 is to demonstrate significant difference in stress response between kidney chips from healthy young individuals in comparison to aged individuals for at least one of the two tested stressors, hypoxia or cisplatin (Milestone 5). This Phase I project will focus on establishing feasibility for future product development and subsequent clinical studies for regulatory approval.